Basement bathroom DWV review/thoughts

Let me start out by thanking everyone for the wealth of knowledge you provide on this site. I have been reading on this site on and off for a couple of years and have gained a lot of plumbing knowledge that I would have otherwise not had.

I am currently designing a bathroom that I would like to put in my basement. I am located in Wisconsin and plan to pull a permit as soon as I have solidified the dwv plans. The following picture is looking toward the bathroom where there will eventually be a door. The green line shows the current 3" waste line. I have punched a hole in the concrete and confirmed the location of the waste line. It is located approximately 1.5 feet under the concrete so I have plenty of height to play with to get 1/4" drop per foot for all waste lines. I didn't model the 1/4" drop per foot but will be sure to include it when actually doing the plumbing. The thin purple line represents 3" pipe, the rest will be 2". The blue pipes are vents which will all tie together in the ceiling and connect to an exisiting 3" vent that runs directly to the roof. I will make sure to slope the vents back toward their respective waste lines in case of condensation, etc. The only san tee in the design is for the lavatory. I will make sure to use long 90's etc and combo Y - 1/8 bend for waste fittings. Sorry as I am not the best using Sketchup, I just wanted to make sure I put together a solid plan.

Front left - corner shower
Back left - corner tub
Front right - cabinet/lavatory
Back right - corner toilet/water closet

Here is a closer picture looking at the plumbing for the toilet and the lavatory. I am attempting to wet vent the toilt and the lavatory but am not really sure that I have done this correctly.

Distances

tub trap to vent - 3.5'
shower trap to vent - 12"
toilet flange top to san tee vent - 5.5' (I may be able to shorten this up some by moving the vent/waste line closer to the toilet but still inside the cabinet. I am not sure the exact length that this can be.)

I would really appreciate some feedback on this layout. If you need any additional pictures or information please let me know and I can provide them. Feel free to comment on simpler/better ways of doing this as I am a novice.

Dimensions of the entire area would be helpful, but given that a 1/4 inch drop per foot slope gives you AT MOST 6 feet before your new 3-inch pipe from the existing line will impact the bottom of the concrete slab, and you still have another 5-1/2 feet between the toilet flange and the vanity, I can't see how you can maintain a 1/4 inch per foot slope from the toilet to the existing line.

Terry - Am I correct in that the pipe should stay 3" all the way up to the lavatory santee, then go to a 2"x1.5" santee? I seems to make sense in my head because then there is internal surface area for water to drain from the lavatory as well as pull air from the vent.

jadziedzic - the room is about 10'x10'. Sorry, I just noticed the mistake in my original post. The waste pipe that is currently there is 1.5 feet down, not 1.5 inches. Thanks for catching that. I would have definately had problems if it was that close to the concrete floor.

Terry - Am I correct in that the pipe should stay 3" all the way up to the lavatory santee, then go to a 2"x1.5" santee? I seems to make sense in my head because then there is internal surface area for water to drain from the lavatory as well as pull air from the vent.

Click to expand...

The vertical section of the wet vent should be 2". The dry vent can be 1.5".

Tom Sawyer - I may be mistaken but I thought I saw in the code book a while back that pipe going into concrete had to be a minimum of 2". That is why I chose 2" instead of the necessary 1-1/2" vent for the tub and shower. I will have to find what I read. Thoughts?

I know this is an old thread, but I just stumbled across it and the plan is surprisingly similar to what I'm going to do for my basement bathroom. One thing I don't see in the plan is a clean-out. Are clean-outs not needed? Also, in my case the nearest venting is on the complete opposite side of the basement from my rough-in. The builder said I can use an AAV instead of an atmospheric vent. So my plan is to put an AAV in the vanity. Here's an image of my rough plan. The left image is the existing rough-in and the right image is how I'm going to change it.